Climate Control Question

[bml66]

Owner of a 91 Roadmaster Wagon with electronic climate control. When I tun on the system the little "F" for Fahrenheit blinks on and off. Never did that before, just started yesterday. It works fine, just was curious what that means.

 

[reure]

From the 91 FSM:

SELF-DIAGNOSTIC FEATURES
If the self-diagnostics feature of the automatic air conditioning system detects a fault while the system is operating, the "°F/°C" symbol to the right of the temperature number will flash very rapidly and the appropriate fault code will be produced by the control assembly microprocessor.
With the exception of Fault Code 09 (Low Freon), fault codes will not be stored in the microprocessor.
As soon as a fault has been detected, the control assembly microprocessor will use a default value (as a parameter value) until the fault is no longer detected.

ENTERING DIAGNOSTIC MODE
To enter the diagnostic mode, the "EXT TEMP" touch switch must be pressed and held while the "OFF" switch is then pressed to enter the command (normally within 5 seconds). Upon entry into the diagnostic mode, the LCD will display any fault codes that are present.

DTC DESCRIPTION
Codes 01/02 Temperature Air Valve Actuator Motor Circuit Fault
Code 03 Outside Air Temperature Sensor Circuit Open
Code 04 Outside Air Temperature Sensor Circuit Short
Code 05 Inside Air Temperature Sensor Circuit Open
Code 06 Inside Air Temperature Sensor Circuit Short
Codes 07/08 Sun Load Sensor Circuit Open or Short
Code 09 Low Freon
Code 10 UART Failure

Clearing Trouble Codes
With the exception of Fault Code 09 (Low Freon), fault codes will not be stored in the microprocessor.
When fault code "09" (Low Freon) is displayed, the fault code can be cleared after servicing the refrigerant system by pressing the "OFF" touch switch while in the diagnostic mode. This also will enable the compressor circuit.

 

[bml66]

Thank you so much for the info! I hope it's not too bad.

 

[nastafarian]

Does anyone have the FSM for 1992 roadmasters? My climate control system is doing the same thing, however i don't have an EXT TEMP button to press...

 

[Ozzy]

neither does mine. The outside temp will display after like 30 seconds without hitting any buttons, its like the clock on the radio comes on after you dont touch any buttons,

 

[wallerus]

According to all data this is how it's done.
ENTERING DIAGNOSTIC MODE

To enter the diagnostic mode, the "TEMP (arrow up)" touch switch must be pressed and held while the "OFF" switch is then pressed to enter the command (normally within 5 seconds). Upon entry into the diagnostic mode, the LCD will display any fault codes that are present.

 

[The Roadmaster]

I asked this in another thread but this is probably the correct venue. My 1991 does not have the Climate Control feature.

What will it take to convert from the basic heater control unit to the climate control unit?

 

[MrBuick (Magnum)]

It takes the wiring harness to it, and the control module under the dash. Works great if you can find a parts car to get the stuff from. Then you need to get a wiring diagram, and tie the harness in. There are some guys who have done it to there 94-96 Chevy Caprices. The wiring would likely be slightly different, as the 91-93's were different than the 94-96's. But otherwise, I think it would be very similar. I can ask the local guy what all he had to do.

 

[The Roadmaster]

And I thank you for the time you take to help!

 

[nastafarian]

bump. sorry mods...😀

 

[MrBuick (Magnum)]

I completely forgot. I will send him a message.

If you wanna ask him he is "94MI9C1" on ISSF.

 

[The Roadmaster]

It takes the wiring harness to it, and the control module under the dash. Works great if you can find a parts car to get the stuff from. Then you need to get a wiring diagram, and tie the harness in. There are some guys who have done it to there 94-96 Chevy Caprices. The wiring would likely be slightly different, as the 91-93's were different than the 94-96's. But otherwise, I think it would be very similar. I can ask the local guy what all he had to do.

Well, I am back to square one. I ordered a new manual heater control and they tried the old bait and switch:

Hello -- I have good news and bad news -- Good news is that we can still get that part from GM's Vintage parts warehouse ( 8 left in the country) The bad news is that Vintage has rights on what they sell it for ,which is ( $ 221.40) - If you would like me to process the order based on the new information, please let me know. -- Thank you, Melissa

From $131 to $221. Told her no thanks. Give me a refund.

With some luck I believe I can convert to the Automatic HVAC system. Aside from the internal and external temp sensors, and a sunlight sensor ... what other components are required aside from the obvious user interface?

 

[MrBuick (Magnum)]

This is what he wrote me:

"Yeah it was lost, it would be easiest for him to find a donor 91 RM and get all the harness and controls out of it, it is a little different than the 94-96 units. He will basically need all of the harness that goes in the dash, there is going to be a mixing valve that is mounted to the blower assembly, resistor module, vacuum module and cabin temp sensor and tube, also the outside temp sensor behind the grill, it is pretty involved, but it can be done. Let me know if you need anymore info.

Mike"

 

[The Roadmaster]

Thanks amigo.